Carburetor



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Z HAROLD ACARLSON OLIN J. EICKMANN ATTORNEY Patented Mar. 33,'194? l stares CABBURETR poration of Delaware Application August 1l, 1943, Serial No. 98,440

scieries.

This invention relates to carburetors for in ternai combustion engines and consists particularly in novel means for controlling the discharge from an accelerating pump particularly of the pressure responsive type.

Wherean automotive engine is provided with a carburetor having an accelerating pump, it is frequently necessary to insure a discharge from the pump immediately the throttle valve is opened even though' the vehicle, at the time, may be coasting with the engine in gear and the carburetor throttle closed. Where an accelerating pump of the pressure responsive type is provided, this requires that the pump piston or diaphragm reach its fully charged position only when the engine suction corresponds with that which exists under such coasting conditions. This suction is vsubstantlally higher than the normal idling suction, and in case of an acceleration -under such coasting conditions, the engine suction may drop from perhaps 24 inches of mercury down to i8 or 19 inches of mercury, which is approximately normal idling suction. An accelerating pump so calibrated, however, has the disadvantage that when the engine is being decelerated by rapid closing of the throttle, a similar variation of engine suction may occur so as to cause a discharge from the accelerating pump,l which is undesirable under these conditions. Re-

, peated deceleration of the engine, as when the An object is to provide a valved vent in a wall v of the pump pressure chamber which is open only when the throttle is closed to relieve pressure built up whether from operation of the pump or the formation of gas inthe fuel.

These objects and other more detailed objects hereafter appearing are attained substantially by the device illustrated in the accompanying drawing in which v i y Fig. l is a vertical sectional view of a carburetor embodying the invention, certain parts being arranged diagrammatically for clearer illustration.

Fig. 2 is a detail view similar to Fig. 1, but showing a modiilcation.

The carburetor shown has a downdrat mixture barrel or conduit including an air inlet horn l, central mixing chamber portion i, including a. series of venturis 3, and an outlet portion il, flanged as at it, for attachment to the engine intake conduit (not shown). The entry ofair into the carburetor is controlled by a choker valve t and the discharge of mixture is controlled by a throttle valve i pivotally mounted on throttle shaft t. Adjacent the barrel is a bowl t within which fuel is maintained at a. substantially constant level by a rloat i@ and the usual needle valve mechanism (not shown). Fuel is supplied to the mixture conduit through a-main metering orifice ii, an upwardly inclined passage lf2, and the main nozzle i3 discharging into the smallest or primary venturi 3. Fuel for idling is supplied through a passage 'id extending upwardly from inclined passage i2 and a downward passage it terminating in idling port i@ adjacent the edge of the throttle when closed. A metering pin il controlling metering orice ii is supported at its upper end on a lever it plvoted above the fuel bowl and connected by a link it to an arm 2d rigid with throttle shaft S.

A capelike casing 2a is attached to one side of fuel bowl S and a diaphragm 2t is secured be-l tween this casing and the bowl wall. The suction chamber 2i on the left side of the diaphragm is connected by a passage 23 to the mixture conduit posterior to 'throttle l. A coiled spring 29 constantly urges the diaphragm toward the right against the force of the eiective suction. The pressure chamber 3@ on the right side of the diaphragm is connected by a cross passage 3i to a valve chamber 32 within which are mounted an inlet check 33 and an outlet check 36. The valve chamber communicates through an inlet passage 35 with the fuel bowl and through an outlet passage te and a restricted nozzle 31 with the mixture conduit.

An ample relief passage $0 connects pump pressure passage 3i with the fuel chamber and this passage is controlled by a valve 6i carried by a goose neck stern t2 .which extends through the bowl cover and thence downwardly and terminates adjacent a second arm'd rigid with throttle shaft 8. A coiled spring s normally maintains valve di seated so as to close relief passage td. Arm d3 is shaped so that when the throttle valve is fully closed, stem s2 and valve 4i are lifted to open the relief passage.

In operatiomengine suction is applied through passage 28 against spring 29 and tends to move diaphragm 26 to the left so as to draw a charge of fuel,from vthe bowl into pressure chamber 30. Spring 29 is calibrated so that the diaphragm does not reach its fully charged position until the engine suction reaches a value of perhaps 24 inches of mercury which is considerably high.. er than normal idling suction. Upon any drop of suction from this value, spring 29 urges the diaphragm to the right so as to force fuel past outlet check 34 and through nozzle 31 into the mixture conduit. However, in case this drop of suction occurs when the throttle is closed, as during rapid deceleration, relief valve v48 will be held open so that the pumped fuel is by-passed through the relatively large relief passage 40 prompt accelerating charge is insured upon a drop of engine suction, during opening of the throttle, but such' dischargel is prevented when the throttle is in closed position regardless of variation in suction.

The modification in Fig. 2 is generally constructed the same as Fig. 1, except for the vent ing the vent, and means for opening the .valve in said vent by said throttle as saidthrottle approaches its closed position to prevent the dis# charge of the fuel inthe pressure chamber into said intake conduit after said throttle is closed 1 2. In a carburetor, means forming a mixture conduit, means forming a constant level fuelnected to said mixture conduit at a point anterior to said throttle. check valves controlling said i pump vinlet and outlet, said pump being con- V instead of through restricted nozzle 31. Thus. a

40a which is located in the top wall ofthe pump Y pressure chamber 30a. The connection 42a to throttle lever 43 operates, as in the flrst form, to hold valve 41a open only when the throttle is closed. Thus, this vent emciently serves to release gas bubbles which may form in the pressure chamber because of excessive heat often created shortly after the engine has stopped. Except for the .vent, such bubbles may cause fuel to spill into the mixture conduit through nozzle 31.

The positioning and arrangement of the pump cut out valve on the outlet side of the pump may be considerably varied and the invention may be otherwise varied as will occur to those skilled in the art without departing from the spirit thereof v and the exclusive use of modifications as come within the scope of the appended claims is contemplated. l

We claim:

1. In a carburetor for an internal combustionv engine, an intake conduit, a throttle therein, a fuel chamber, an accelerator pump having a suction responsive element operable in the charging direction in response to intake suction posterior to said throttle, said suction responsive element being movable to fully charged position responsive to suction substantially higher than the suction at normal idling. inlet and outlet ports for said pump, inlet and outlet check valve Acontrolling said ports, a fuel pressure chamber connecting the pump with said ports, an outlet passage connected to the outlet port of said pumpl and discharging into said intake conduit at a point anterior to said throttle valve, a vent in the upper wall of said pressure chamber discharging into said fuel chamber, a valve for normally clos- Number structed and arranged to discharge upon a decrease in suction at a point posterior to said throttle, a by-pass to permit fuel to be discharged from said pump to vsaid fuel chamber without flowing through said. discharge outlet, a yvalve normally closing said by-pass, and means operated by vsaid throttle as it approaches its. closed position for opening said by-pass valve to permit the discharge of fuel from said pump.

3. In a carburetor, means forming a fuel miicture conduit, means forming a constant level fuel chamber, a throttle for said mixture conduit, a suction charged pump having a pump chamber, an inlet passage connecting said pump chamber to said fuel chamber and an outlet passage for said pump discharging into said mixture conduit at a point anterior to the throttle, check valves controlling said inlet and outlet passages, said pump having spring means arranged to discharge the uid in the pump chamber upon a decrease in suction, a by-pass to permit fuel to be discharged from said pump to said fuel chamber without flowing through said discharge outlet, a valve controlling said by-pass, and means for opening said by-pass valve by the throttle when the latter 'approaches closed position.

The following references are of record in the ille of this patent:

UNITED STATES PATENTS Name Date 1,948,999 Westcott Feb. 27, 1934 2,021,694 Messinger, Jr Nov. 19, 1935 2,133,033 Messinger, Jr. Oct. 11, 1938 2,136,959 Winfield Nov. 15. 1938 2,230,144 Kittler Jan. 28, 1941 v 2,235,797 Carlson Mar. 18, 1941 FOREIGN PATENTS Number Country Date i' British May 15, 1940 

